feat: add inverted text style

[officialasishkumar]

What It Does

Adds support for inverted text styling, backed by crossterm's reverse video attribute.

This adds an invert flag to CanvasTextStyle, exposes the same option on Text, and adds an invert() builder method for MixedTextContent. ANSI rendering now emits Attribute::Reverse when inverted text begins and resets when it ends.

Focused tests cover ANSI output, direct canvas cell style access, Text, and MixedText.

Related Issues

Fixes #108

[ccbrown]

Thanks for the PR! One comment but otherwise lgtm!

[ccbrown]

There shouldn't be any need to add italic to the check here since the state of the italic attribute doesn't impact the rendering of empty cells.

Suggested change

	} else if text_style.underline || text_style.italic || text_style.invert {
	} else if text_style.underline || text_style.invert {

[officialasishkumar]

Removed the unnecessary italic check for empty cells. cargo test -p iocraft passes. Commit: b3feeeb

[codecov]

Codecov Report

❌ Patch coverage is 97.82609% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 88.00%. Comparing base (4c8bf90) to head (b3feeeb).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
packages/iocraft/src/canvas.rs	96.55%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #196      +/-   ##
==========================================
+ Coverage   87.92%   88.00%   +0.07%     
==========================================
  Files          35       35              
  Lines        5617     5662      +45     
  Branches     5617     5662      +45     
==========================================
+ Hits         4939     4983      +44     
  Misses        569      569              
- Partials      109      110       +1     

Files with missing lines	Coverage Δ
packages/iocraft/src/components/mixed_text.rs	93.10% <100.00%> (+0.79%)	⬆️
packages/iocraft/src/components/text.rs	99.64% <100.00%> (+<0.01%)	⬆️
packages/iocraft/src/canvas.rs	95.20% <96.55%> (+0.05%)	⬆️

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[ccbrown]

Thank you!